METHODS OF COMBATING FUNGUS DISEASE ON FISHES 

IN CAPTIVITY 

By Charles F. Holder 

Paper presented before the Fourth International Fishery Congress 
held at Washington, U. S. A., September 22 to 26, 1908 

BULLETIN OF THE BUREAU OF FISHERIES :::::: VOL. XXVIIl. P. 933 -936 
Document No. 692 : : : : : : ::■::::::::::::: Issued AprU, 1910 



^iH 



933 



APR 16 1910 






METHODS OF COMBATING FUNGUS DISEASE ON FISHES IN 

CAPTIVITY. 

By CHARLES F. HOLDER. 

The few suggestions made in this connection are the resuh of observations 
made in several tank aquariums and a series of open-reef aquariums on the 
Florida coast for the study of corals and fishes. 

Fishes in confinement are subject to fungus disease in a ratio as the conditions 
under which they are kept differ from those of their normal habitat. Such 
differences vary largely with the intelligence or ignorance of the keepers, or their 
carelessness. Fishes are handled improperly, have been injured previously or 
in their capture; they are overfed and food collects in the tanks; aeration is 
incomplete ; there is an overabundance of algae ; or the cement of the tank may 
be poisonous. All these factors are causes of disease, as I observed in the 
New York Aquarium in 1873, in the Santa Catalina Zoological Station in 
1 903- 1 908, and in Florida where aquariums were built out into the reef. 

It has been my experience, then, that if preventive measures are sufficient 
few fish are diseased or lost, and the point of my suggestions relating to fungus 
affecting a species of fish under cultivation is that the Chinese method of materia 
medica should be adopted — namely, not to cure but to keep well. A set of 
rules bearing on the prevention of disease should be observed by every aquarium 
attendant. Such rules are as follows: 

I. Never take out fish with the bare hands. Lift them carefully with a 
large fine-mesh net. Under no circumstances touch them, as handling often 
produces fungus. 

II. Give the fish proper and natural aeration. The surf or near-shore fishes 
require more or direct aeration ; deep water forms require less. 

III. Never allow food to collect in the tank. Have every tank supplied with 
an abundance of natural scavengers — crabs of various kinds, barnacles (sea 
water). In fact, it should be the most important qualification of an attendant 
to know how to equip a tank to give the fish natural surroundings. The habits 
of the fish should be known, its usual food given it, and the balance should be 
preserved in the tanks, each being supplied, so far as possible, with the conditions 
found in natural life. 

The following are some experiments successfully tried at the Avalon 
Zoological Station. 

935 



936 BULLETIN OF THE BUREAU OF FISHERIES. 

1. Fungus growth developed on sculpins. Investigation showed that there 
were 50 per cent too many in the tank. The fish, a near-shore, rocky-bottom 
species, needed maximum aeration; this was increased and in a few weeks the 
fishes were in the best of condition. 

2. Male sheepshead constantly died because attacked with a virulent fungus ; 
swam at the surface with the head out of water; showed bruises over body, 
and lacerated fins. Attendant diagnosed the case as "fish sickness." The 
habits of the fish were carefully studied, a man watching them even at night. 
This watcher reported that as soon as the lights went out the largest males 
attacked the other males furiously and repeatedly bit and lacerated them. 
The next day two sheepshead tanks were arranged, each with one male to ten 
or twelve females. In these there was no more difficulty with fungus growth. 

3. Surf-fish were attacked with malignant fungus growth. They were in a 
tank with air coming up through the bottom, thus receiving the minimum 
amount of aeration. The surf -fish in California lives near the surf and requires 
the rush of well aerated water. Surface aeration of a violent kind was provided 
and the fishes recovered at once. 

4. A mysterious illness attacked rock bass. Examination of the tank showed 
poor sanitary conditions. The fish were invariably overfed, the debris col- 
lected at the bottom, and the underside of the rocks was covered with "white." 
Feeding was stopped for several days, a larger per cent of salt introduced, 
and scavengers — hermit crabs, mollusks of various kinds — were put into the 
tank. In two weeks the tanks were completely sanitary. 

5. Fish in a standing tank were troubled with fungus growth. It was sus- 
pected that the evaporation (near sunlight) was too rapid, and fresh water was 
added, a quart at a time. The fishes recovered, apparently showing the trouble 
to be too much salt. 

Briefly, I would advocate, instead of elaborate and expensive treatment of 
fishes, prevention; in other words, a study of the habits of fishes, so that each 
one kept in confinement may be given the conditions and environment it 
requires. If this is done, at least in my experience it has so proved, fungus disease 
need not be dreaded, as it will not appear. 

As to treatment for fungus, however, if the fish is a common one and easily 
replaced, as trout, remove and destroy it at once and waste no time on it. If 
the fish is rare and treatment is necessary, remove it to a new tried tank and 
double or quadruple the aeration from overhead or direct fall. See that the 
tank has scavengers (crabs) sufficient to keep it perfectly pure and clean. If 
fungus has developed, take the fish out, using gloves, and wipe the spots with a 
sponge dipped in a strong solution of salt and water. Stop feeding for a few 
days; then give the fish its natural food, if this can be determined. 



METHODS OF COMBATING FUNGUS DISEASE ON FISHES 

IN CAPTIVITY 

By Charles F. Holder 

Paper presented before the Fourth International Fishery Congress 
held at Washington. U. S. A., September 22 to 26. 1908 

BULLETIN OF THE BUREAU OF FISHERIES : : : : : : VOL. XXVIII. P. 933 ^36 

Documeni No. 692 :::::: :::::;:::::::::; Issued April. 1910 



933 






.^ 



\^ 



K?^^ 

% 






METHODS OF COMBATING FUNGUS DISEASE ON FISHES IN 

CAPTIVITY. 

By CHARLES F. HOLDER. 

The few suggestions made in this connection are the result of observations 
made in several tank aquariums and a series of open-reef aquariums on the 
Florida coast for the study of corals and fishes. 

Fishes in confinement are subject to fungus disease in a ratio as the conditions 
under which they are kept differ from those of their normal habitat. Such 
differences vary largely with the intelligence or ignorance of the keepers, or their 
carelessness. Fishes are handled improperly, have been injured previously or 
in their capture; they are overfed and food collects in the tanks; aeration is 
incomplete ; there is an overabundance of algae ; or the cement of the tank may 
be poisonous. All these factors are causes of disease, as I observed in the 
New York Aquarium in 1873, in the Santa Catalina Zoological Station in 
1 903- 1 908, and in Florida where aquariums were built out into the reef. 

It has been my experience, then, that if preventive measures are sufficient 
few fish are diseased or lost, and the point of my suggestions relating to fungus 
affecting a species of fish under cultivation is that the Chinese method of materia 
medica should be adopted — namely, not to cure but to keep well. A set of 
rules bearing on the prevention of disease should be observed by every aquarium 
attendant. Such rules are as follows: 

I. Never take out fish with the bare hands. Lift them carefully with a 
large fine-mesh net. Under no circumstances touch them, as handling often 
produces fungus. 

II. Give the fish proper and natural aeration. The surf or near-shore fishes 
require more or direct aeration ; deep water forms require less. 

III. Never allow food to collect in the tank. Have every tank supplied with 
an abundance of natural scavengers — crabs of various kinds, barnacles (sea 
water). In fact, it should be the most important qualification of an attendant 
to know how to equip a tank to give the fish natural surroundings. The habits 
of the fish should be known, its usual food given it, and the balance should be 
preserved in the tanks, each being supplied, so far as possible, with the conditions 
found in natural life. 

The following are some experiments successfully tried at the Avalon 
Zoological Station. 

935 



fill II Mill I III! INI II 
002 869 833 1 



936 BULLETIN OF THE BUREAU OF FISHERIES. 

1 . Fungus growth developed on sculpins. Investigation showed that there 
were 50 per cent too many in the tank. The fish, a near-shore, rocky-bottom 
species, needed maximum aeration; this was increased and in a few weeks the 
fishes were in the best of condition. 

2. Male sheepshead constantly died because attacked with a virulent fungus ; 
swam at the surface with the head out of water; showed bruises over body, 
and lacerated fins. Attendant diagnosed the case as "fish sickness." The 
habits of the fish were carefully studied, a man watching them even at night. 
This watcher reported that as soon as the lights went out the largest males 
attacked the other males furiously and repeatedly bit and lacerated them. 
The next day two sheepshead tanks were arranged, each with one male to ten 
or twelve females. In these there was no more difficulty with fungus growth. 

3. Surf-fish were attacked with malignant fungus growth. They were in a 
tank with air coming up through the bottom, thus receiving the minimum 
amount of aeration. The surf -fish in California lives near the surf and requires 
the rush of well aerated water. Surface aeration of a violent kind was provided 
and the fishes recovered at once. 

4. A mysterious illness attacked rock bass. Examination of the tank showed 
poor sanitary conditions. The fish were invariably overfed, the debris col- 
lected at the bottom, and the underside of the rocks was covered with "white." 
Feeding was stopped for several days, a larger per cent of salt introduced, 
and scavengers — hermit crabs, mollusks of various kinds — were put into the 
tank. In two weeks the tanks were completely sanitary. 

5. Fish in a standing tank were troubled with fungus growth. It was sus- 
pected that the evaporation (near sunlight) was too rapid, and fresh water was 
added, a quart at a time. The fishes recovered, apparently showing the trouble 
to be too much salt. 

Briefly, I would advocate, instead of elaborate and expensive treatment of 
fishes, prevention; in other words, a study of the habits of fishes, so that each 
one kept in confinement may be given the conditions and environment it 
requires. If this is done, at least in my experience it has so proved, fungus disease 
need not be dreaded, as it will not appear. 

As to treatment for fungus, however, if the fish is a common one and easily 
replaced, as trout, remove and destroy it at once and waste no time on it. If 
the fish is rare and treatment is necessary, remove it to a new tried tank and 
double or quadruple the aeration from overhead or direct fall. See that the 
tank has scavengers (crabs) sufficient to keep it perfectly pure and clean. If 
fungus has developed, take the fish out, using gloves, and wipe the spots with a 
sponge dipped in a strong solution of salt and water. Stop feeding for a few 
days; then give the fish its natural food, if this can be determined. 



